The invention relates to improvements in apparatus for applying films or coats of flowable material to selected sides of running flexible webs of paper or the like. Typical examples of such apparatus are pasters which are utilized in so-called filter tipping machines to coat one side of a running web of so-called tipping paper (such as cigarette paper or imitation cork) with a suitable adhesive. The web of adhesive-coated tipping paper is thereupon severed at regular intervals to yield discrete sections or patches, called uniting bands, which are ready to be convoluted around groups of coaxial plain cigarettes, cigarillos or cigars and filter rod sections of unit length or multiple unit length to form therewith filter cigarettes, cigars or cigarillos of unit length or multiple unit length.
A filter tipping machine wherein a paster is used to coat one side of the running web of tipping paper with a film of adhesive (such as hot melt) is disclosed, for example, in U.S. Pat. No. 4,249,547 granted Feb. 10, 1981 to Hinzmann for "METHOD AND APPARATUS FOR APPLYING ADHESIVE TO RUNNING WEBS OF WRAPPING MATERIAL" and in the corresponding published German patent application Serial No. 30 13 979 A1.
Published German patent application Serial No. 43 09 951 of Berger discloses a paster which can be utilized to coat one side of a running web of tipping paper with a suitable adhesive substance. This paster employs a plenum chamber wherein the pressure of confined adhesive varies as a function of the speed of a rotor having a profiled peripheral surface serving to transfer an adhesive pattern to one side of a web which is advanced through a coating station where the one side of the web comes in contact with the adhesive furnished by the profiled peripheral surface of the rotor. The latter cooperates with a roller which bears upon the upper sides of successive increments of the running web to thus urge the underside of the web against the profiled peripheral surface of the rotor.
A drawback of the just discussed paster is that the roller is likely to squeeze a certain percentage of applied adhesive beyond the marginal zones of the web so that the thus expelled adhesive contaminates the parts which guide the coated web on its way toward the severing or subdividing station. The displaced adhesive is also likely to contaminate (and to thus render necessary frequent cleaning of) the component parts of the device which repeatedly severs the leader of the coated web to form a file of discrete adhesive-coated uniting bands ready to be used to unite tobacco-containing rod-shaped articles with filter rod sections.
The aforementioned U.S. Pat. No. 4,249,547 to Hinzmann discloses an apparatus which is designed to apply to one side of a running cigarette paper web or the like a pattern of adhesive patches or fields including patches having a greater thickness and patches of lesser thickness. This can result in undesirable flow and in less than satisfactory distribution of flowable adhesive while the uniting bands are being convoluted around the abutting end portions of filter mouthpieces and rod-shaped tobacco containing sections, such as plain cigarettes of unit length or multiple unit length. Thus, whereas the application of adhesive patterns having portions or sections of different thicknesses can reduce the likelihood of contamination of parts (such as pulleys, walls or the like) which guide the coated web to severing and filter tipping stations, the adhesive is more likely to contaminate the ultimate products, such as filter cigarettes, cigars or cigarillos.
The entire disclosures of the aforementioned German patent applications Serial Nos. 30 13 979 A1 of Hinzmann and 43 09 951 of Berger are also to be considered as being incorporated by reference into the specification of the present application.